How expensive are autonomous cars?

When brake pads need replacement, vehicles usually alert the driver through multiple signals. The most obvious sign is a sharp metal scraping noise during braking, which directly results from the wear indicator contacting the brake disc, indicating the brake pads are severely worn to their limit and require immediate replacement to prevent brake disc damage. If the brake pedal's travel becomes noticeably longer or feels softer with reduced braking force, this may be due to excessively thin brake pads or insufficient brake fluid, necessitating prompt inspection. The illumination of the brake warning light on the dashboard (such as an exclamation mark in parentheses ⓘ or the "BRAKE" indicator) is the vehicle computer's explicit replacement command and should not be ignored. Additionally, vehicle pulling during emergency braking or persistent "grinding" noises when lightly applying the brakes both signal that the brake pads' friction material is nearly depleted. Regular inspection of brake pad thickness is advised. New pads measure approximately 1.5 cm thick and should be replaced when worn down to 5 mm (about one-third of original thickness) or when level with the wear indicator. Front brake pads typically require priority inspection every 30,000-40,000 kilometers, while rear pads, though longer-lasting, still demand attention. Upon noticing any of these warning signs during daily driving, immediate brake system servicing is essential to ensure safety and reliability.

When brake pads require replacement, a distinct metallic friction sound will occur. This sharp and piercing "hissing" noise is particularly noticeable when lightly applying the brakes, resulting from direct contact between the wear indicator and brake rotor after the pads have worn down to their limit. Simultaneously, the brake pedal will feel softer with increased travel distance, requiring deeper depression to achieve normal braking force. Some vehicle models may illuminate a dashboard warning light featuring either an encircled exclamation mark (ⓘ) or the "BRAKE" indicator. Regular inspection of pad thickness through wheel spoke gaps is recommended. New pads measure approximately 15mm thick, requiring immediate replacement when worn down to 3mm or one-third of their original thickness. Front brake pads typically require thorough inspection every 30,000-40,000 kilometers, while rear pads generally last longer. Ignoring these warning signs may not only damage costly brake rotors but could also compromise braking performance, creating safety risks with potential repair costs exceeding RM2,000. During normal operation, extended stopping distances or vehicle pulling during hard braking should prompt immediate brake pad inspection.

It is relatively rare for brake pads to wear down to the point of needing replacement within 3 months, but it is not impossible, depending on driving conditions and habits. Typically, front brake pads last between 30,000 and 50,000 kilometers, while rear brake pads last between 60,000 and 100,000 kilometers. However, frequent hard braking, mountain driving, heavy loads, or congested road conditions can significantly accelerate wear. If the driving style is aggressive or the vehicle is used in harsh road conditions for extended periods, brake pads may wear down to the safety limit (below 3mm) in a short time, at which point warning signs such as increased braking distance, metallic grinding noises, or a spongy brake pedal will appear. According to the 2025 National Automobile Safety Standards, brake pads with a thickness below 3mm must be replaced immediately, while those at 5mm remain within the safe range but require assessment based on operating conditions. It is recommended to visually inspect brake pad thickness monthly (new pads measure approximately 15mm). If abnormal wear or rapid thickness reduction is observed, prompt servicing should be performed to prevent damage to the brake rotors. Minimizing hard braking and utilizing engine braking in daily driving can prolong brake pad life, and technicians should always be instructed to inspect the braking system condition during routine maintenance.

Replacing brake pads on one's own is feasible for car owners with basic mechanical knowledge and tools, but it is necessary to comprehensively consider vehicle model differences, operational complexity, and safety risks. For small sedans, due to their thinner brake pads and simpler wheel hub design, the replacement difficulty is relatively low; usually, it can be completed just by removing the tires and loosening the caliper bolts. However, for SUVs or high-performance cars, the operational threshold is higher because their brake pads are thicker or require special tools. Before replacement, it is necessary to check whether the remaining thickness of the brake pads is less than 5 millimeters (or 1/3 of the original thickness). If abnormalities such as metal friction noise or a soft brake pedal occur, immediate action is required. During operation, attention should be paid to details such as caliper resetting and bolt torque. After replacement, a break-in period of 200 kilometers is needed, and sudden braking should be avoided. If one lacks experience or tools, it is recommended to choose a professional repair shop, as improper installation may lead to uneven braking or caliper damage, affecting driving safety. Check the wear status of brake pads regularly every 5,000 kilometers. Combining this with driving habits (for example, frequent braking in urban areas may shorten the replacement cycle to 30,000 kilometers, while high-speed driving can extend it to 80,000 kilometers) can help more accurately determine the optimal replacement time.

The replacement interval for brake pads should be determined by comprehensively considering driving habits, vehicle model, and actual wear conditions. Generally, front brake pads are recommended for inspection and replacement every 30,000 to 50,000 kilometers, while rear brake pads every 60,000 to 100,000 kilometers, but specific intervals should follow the manufacturer's manual. New brake pads are approximately 1.5 cm thick. Replacement is mandatory when the remaining thickness falls below 3 mm or wears flush with the grooves. Some vehicle models provide dashboard warning alerts. Immediate inspection is required if any of the following occurs: sharp noises during light braking, increased stopping distance, or abnormal pedal travel. Vehicles with aggressive driving styles, frequent city driving, or regular mountain road use experience accelerated brake pad wear and may require earlier replacement; conversely, highway-dominant vehicles can extend the service interval. It is advisable to inspect brake pad condition every 5,000 kilometers, including thickness, wear uniformity, and retraction performance. During replacement, prioritize OEM or certified brand products and ensure simultaneous replacement of left and right wheel units to maintain braking balance. DIY inspection can estimate remaining thickness through wheel rim observation, but the most accurate method involves tire removal for direct measurement. Metallic grinding noises indicate near-limit wear, necessitating prompt attention to prevent brake rotor damage.